Apparatus for indicating the air content of concretes and mortars



June 30,1959 HACE 2,892,343

' APPARATUS FOR INDICATING THE AIR CONTENT 0F CONCRETES AND MORTARS Filed July 27, 1955 Mm; .LMCA a as ATTORNEY;

United States atent APPARATUS FOR INDICATING THE AIR 110N- TENT F CGNCRETES AND MQRTARS Leroy M. Chace, North Bridgtou, Maine Application July 27, 1955, Serial No. 524,746

1 Claim. (Cl. 73-19) The present invention relates to apparatus for indicating the percentage of air content entrained in a concrete or mortar mix, and more particularly to such devices that can be used to obtain the indication in a relatively limited period of time.

The primary object of the invention is to provide an apparatus for testing the air content of concrete and mortar mixes having entrained air contained therein in a manner and with an apparatus which permits the test to be conducted in the field in a very limited period of time so that there will be no appreciable delay in the pouring of the mix while the test is being conducted.

Concrete and mortar mixes having entrained air therein have been found to protect the mix from damage due to freezing and thawing, and in addition the entrained air acts as a lubricant for the mixture, permitting a reduction in the normal water and sand content. In the case of air being entrained in a concrete mix, where the water and sand content remains the same, there will be a loss of strength in the concrete to some extent. However, such loss of strength can be largely overcome by reducing the Water and sand content, as mentioned above. Furthermore, the air bubbles entrained in the concrete protects the concrete against the deleterious eifects of the snow melting salts, such as calcium chloride CaCl The air bubbles are created and entrained in the concrete mix by means of chemicals exerting a surface chemical action on the mix. It has been found that in mortars involving a fine sand mix, a 14% to 20%, by volume, air entrainment produces the desired results, while it has also been found that in some concrete mixtures a 3% to 6%, by volume, air entrainment produces the desired results. In such instances the bubbles will be quite small and should be spaced approximately A of an inch apart. Before concrete is poured, it is important that the mix be tested to determine if the volume of air contained therein is sufficient to produce the optimum results desired so that the mix can be accepted or rejected before it is poured. The present mechanisms and methods provided for the purpose require approximately one-half hour to conduct the test and must be conducted by an experienced engineer or chemist.

A further object of the invention is to provide an apparatus for testing and indicating air entrainment in concrete and mortar mixes which can be conducted by relatively unskilled persons with a high degree of accuracy.

Other objects and advantages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure 1 is a side elevation, shown partly in section, of the stopper and measuring cup;

Figure 2 is a vertical cross section of the tube showing fluid contained therein;

Figure 3 is a side elevation of the tube showing the stopper and measuring cup inserted therein, and

Figure 4 is a view of the tube with the stopper and measuring cup inserted therein, with the tube inverted showing the liquid level resulting from the test.

Referring now to the drawings in detail wherein like reference numerals indicate like parts throughout the several figures, the reference numeral 10 indicates generally a tube for holding the materials to be tested as the test is conducted. The tube 10 comprises a cylindrical barrel portion 11 having an open end 12, with the opposite end reduced as at 13 and joined to a tube 14 extending therefrom with the tube 14 and the barrel 11 having a common axis. The tube 14 is calibrated as at 15 and has the outer end open as at 16. The open end 16 of the tube 14 is terminated smoothly to provide a seat for engagement of the users finger. A rubber stopper 17 is adapted to be positioned Within the barrel 11, as illustrated in Figures 3 and 4. The inner smaller end 18 of the stopper 17 has secured thereto an upstanding cylindrical cup 19 which is formed from plastic, metal or the like, and glued or otherwise secured at 20 to the end 18 of the stopper 17.

In testing the air content of concrete, the following method is used. The stopper 17 is removed from the barrel 11 and inverted so that the cup id is upright. The concrete mix excluding particles larger than No. 10 is placed in the cup 19 and then rodded with a small knife blade or wire to compact the mix. The excess is struck off with a straight edge to insure the accuracy of the measurement. The barrel 11 is then filled with an isopropyl alcohol with the end 16 of the tube 14 sealed by a finger 21. The isopropyl alcohol is filled to the line 22 on the barrel 11. The stopper 17 is inserted into the barrel 11, With the cup 19 extending inwardly of the barrel 11 so that the concrete mix contained therein will be within the barrel 11. The barrel 11 is then inverted and the tube 14 is filled with isopropyl alcohol to the top, being careful to note any air bubbles and permit their escape. Finger 21 is then replaced on the open end 16 of the tube 14 and the barrel 11 is then gently rolled from vertical to horizontal several times until all of the mix has been dissolved out of the cup 19 into the alcohol. Then the indicator is turned so that the tube 14 is uppermost and the new level 23 of the isopropyl alcohol in the tube 14 is noted. The difierence between the level in the tube 14 prior to mixing the concrete with the alcohol, with the level in the tube 14 after the mixing has taken place, is equal to the volume of air contained in the concrete mix in the cup, and by the calibrations indicates a percentage of air in a cubic yard of the concrete mix.

Having thus described the preferred embodiment of the invention, it should be understood that structural changes in the apparatus may be resorted to without departing from the scope of the appended claim.

What is claimed is:

An apparatus for measuring the volume of air in a measured volume of fluid concrete comprising an elongated cylindrical barrel of transparent material having an open end, an elongated tube of transparent material, said tube having a diameter substantially smaller than the diameter of said barrel, a reduced end portion integrally formed on the other end of said barrel joining said barrel integrally to one end of said tube in axially aligned relation, said tube having the other end thereof open, said tube having scale markings thereon, a stopper telescopically inserted in the open end of said barrel, a measuring cup integrally secured to the inner end of said stopper, said cup being adapted to be filled with a measured amount of fluid concrete and mixed with a measured volume of isopropyl alcohol contained in said barrel.

References Cited in the file of this patent UNITED STATES PATENTS 2,635,459 Gray Apr. 21, 1953 2,722,825 Meyer Nov. 8, 1955 OTHER REFERENCES Journal of the American Chemical Society, vol. 18, No. 9, May 1947, Carl Menzel, pages 1053-1072. 

